Ford super duty 3.31 rear end. Will it be a big mistake. ?

Lantley wrote:
I 'll take slightly better over slightly worse every time.
I'm not sure why some feel the need to go through a lot of mumbo jumbo and tech speak to reach the slightly better conclusion.
The higher ratio will always tow better.
3.31 and 3.55 are pretty close to start with but the higher ratio still performs better when towing. Calculating a performance standard that uses 30" tires is misguided and misleading. Very few are towing RV's with 30+" tires

Consider this: To get your trailer moving your current truck starts out in 1st gear and with 3.73 rear gears the 910 lbft of engine torque is multiplied:

3.73 x 3.094 = 11.54 times giving you potentially 910 x 11.54 = 10,500 lbft to the rear wheels.

The torque to the rear wheels of the new Ford with its ten speed transmission and a 3.31 rear end looks something like this
3.31 x 4.615 = 15.28 which could potentially put 15.28 x 1050 = 16,044 lbft of torque to the rear axle.

To get 16,044 lbft of torque to the rear axle of your 2019 GM you would need a 5.70:1 rear end.

My point is that 3.31 gears with a ten speed is far more than slightly better than what you are used to. When we are only pulling 16,000 to 18,000 lb rvs 16,000 lbft of torque is tremendous. Having 10 gears to choose from is really kind of over kill while pulling loads that the SRW trucks are capable of. Realize that 9th with 3.31 final drive is near identical to 10th with 3.55 gears. So the 3.31 equipped truck has tremendous capability to get our relatively light trailers moving in 1st gear, has more than enough gears to keep the engine at it's peak operating range while towing heavy or in the hills and has a 10th gear that can be utilized for optimum fuel economy when towing on flat ground or not towing. People are free to choose a 3.55 gear ratio for their SRW diesel and they will be happy but they are giving up a little economy to gain nothing.